U.S. patent application number 10/853245 was filed with the patent office on 2004-12-02 for fingerprint input device and personal authentication system utilizing the same.
This patent application is currently assigned to CANON KABUSHIKI KAISHA. Invention is credited to Hata, Fumio.
Application Number | 20040240713 10/853245 |
Document ID | / |
Family ID | 33447744 |
Filed Date | 2004-12-02 |
United States Patent
Application |
20040240713 |
Kind Code |
A1 |
Hata, Fumio |
December 2, 2004 |
Fingerprint input device and personal authentication system
utilizing the same
Abstract
The invention provides a fingerprint input device with a small
area and a compact structure, and being manufactured in a simple
process, comprising an LED for emitting into a finger a light, an
image pickup unit for receiving the light scattered inside the
finger, a peripheral circuit unit connected to the image pickup
unit 1a, a silicon chip 1 bearing image pickup elements
constituting the image pickup unit and the peripheral circuit unit,
and a fiber optics plate fixed on the silicon chip, having a
surface on which the finger is placed and constituting light
transmission means for transmitting the light, scattered inside the
finger placed on the surface to the image pickup element along a
direction inclined by a predetermined angle. At least a part of the
peripheral circuit unit is formed on the silicon chip opposed to a
non-light-transmitting area of the fiber optics plate.
Inventors: |
Hata, Fumio; (Tokyo,
JP) |
Correspondence
Address: |
FITZPATRICK CELLA HARPER & SCINTO
30 ROCKEFELLER PLAZA
NEW YORK
NY
10112
US
|
Assignee: |
CANON KABUSHIKI KAISHA
Tokyo
JP
|
Family ID: |
33447744 |
Appl. No.: |
10/853245 |
Filed: |
May 26, 2004 |
Current U.S.
Class: |
382/124 |
Current CPC
Class: |
G06V 40/1318
20220101 |
Class at
Publication: |
382/124 |
International
Class: |
G06K 009/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 28, 2003 |
JP |
2003-150901 |
Claims
What is claimed is:
1. A fingerprint input device including a light source for emitting
a light into an interior of a finger of a fingerprint inputting
person, an image pickup unit for receiving the light emitted from
said light source and scattered in the interior of said finger, and
a peripheral circuit unit connected to said image pickup unit
thereby reading a fingerprint image of said finger based on a light
reception signal of said image pickup unit through said peripheral
circuit unit, the device comprising: a semiconductor substrate
bearing an image pickup element constituting said image pickup unit
and said peripheral circuit unit; and an inclined fiber optics
plate, fixed on said semiconductor substrate, having a surface on
which the finger of said fingerprint inputting person is placed and
constituting light transmission means for transmitting the light,
scattered from the interior of said finger placed on said surface,
to said image pickup element along a direction inclined by a
predetermined angle; wherein at least a part of said peripheral
circuit unit is formed on said semiconductor substrate opposed to a
light non-transmitting area of said inclined fiber optics
plate.
2. A fingerprint input device according to claim 1, wherein at
least a part of said peripheral circuit unit is formed on said
semiconductor substrate opposed to the light non-transmitting area
of said inclined fiber optics plate and/or on said semiconductor
substrate where said inclined fiber optics plate is not in
contact.
3. A fingerprint input device according to claim 1 or 2, wherein
said image pickup unit is constituted of image pickup elements of a
predetermined dimension and is adapted to collectively read,
through said image pickup elements, a fingerprint image of said
finger placed on the surface of said inclined fiber optics
plate.
4. A fingerprint input device according to claim 1 or 2, wherein
said image pickup unit is constituted of image pickup elements of a
predetermined dimension and is adapted to collectively read,
through said image pickup elements, a fingerprint image of said
finger placed on the surface of said inclined fiber optics plate,
while said finger is made to slide in a predetermined direction
along said surface.
5. A fingerprint input device according to claim 4, wherein fibers
constituting said fiber optics plate are arranged in an inclined
manner along a predetermined direction.
6. A fingerprint input device according to claim 1, wherein said
inclined fiber optics plate is covered in all of end portions
thereof or a part thereof with an opaque resin.
7. A personal authentication system characterized in comprising a
fingerprint input device according to claim 1.
8. A personal authentication system according to claim 7, further
comprising: fingerprint registering means which registers in
advance a fingerprint image of a finger, read by said fingerprint
input device, as identification information for a person; and
fingerprint verification means which verifies whether the
fingerprint image of said finger, read by said fingerprint input
device matches with the image registered in said fingerprint
registering means, and outputs a result of the verification as a
personal authentication signal.
9. An electronic equipment characterized in comprising the personal
authentication system according to claim 7 or 8.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an ultra compact
fingerprint input device, and more particularly to a fingerprint
input device of in-finger scattering type in which a fiber optics
plate constituting light transmitting means is fixed on a silicon
chip bearing an image pickup element, and the interior of a finger
placed on a surface of the fiber optics plate is irradiated with an
infrared light, a near infrared light, a red light etc. and a light
scattered from the interior of the finger is received through the
fiber optics plate with the image pickup element to read the
fingerprint of the finger.
[0003] 2. Description of the Related Art
[0004] With the recent pervasiveness of the electronic trading and
similar economic activities based on the remarkable progress in the
information technologies, the necessity for electronic personal
authentication is increasing for the purpose of avoiding improper
use of information.
[0005] For electronic personal authentication, there have been
employed various methods of inputting an image of a fingerprint.
For example Japanese Patent Application Laid-open No. 2000-21780
discloses a method of emitting a near infrared light toward the
interior of a finger, maintained in contact with the vicinity of a
surface of a two-dimensional image pickup element and receiving a
scattered light from the interior of the finger. This method allows
to construct an extremely compact fingerprint input device without
requiring a total reflecting prism or the like.
[0006] However, a semiconductor, including a solid image pickup
element, is generally very fragile, and is easily broken by an
application of a physical force or an electrostatic charge, or a
deposition of moisture or salt caused by a direct contact of a
finger or the like. In order to prevent such damage, light
transmission means such as a fiber optics plate (hereinafter also
represented as FOP) is usually adhered onto the silicon chip. The
FOP is formed by adhering and cutting out a bundle of glass optical
fibers, and can provide a chemical stability and strength far
superior to those of the silicon chip at a suitably selected
thickness.
[0007] Also as disclosed in Japanese Patent Application Laid-open
No. 7-174947, it is known that a clear fingerprint image can be
obtained by a suitable selection of an inclination angle .alpha. at
the cutting of the FOP, as the light from a portion in contact with
the fingerprint is easily transmitted while the light from other
parts in contact with the air is scarcely transmitted. A prior
configuration disclosed in Japanese Patent Application Laid-open
No. 7-174947 is shown in FIG. 5.
[0008] Referring to FIG. 5, an FOP 3 on which a finger of a
fingerprint inputting person is fixed by adhesion to an image
pickup unit 1a on a silicon chip 1. An inclination angle .alpha. of
the FOP 3 is about 30.degree., generally within a range of 20 to
40.degree., though an optimum value is variable depending on a
refractive index of the optical fibers constituting the FOP.
[0009] The FOP is generally prepared by forming a bundle of a
plurality of extremely fine optical fibers, then fixing the fibers
under heat and pressure to obtain an ingot (block), cutting and
polishing such ingot at a predetermined inclination angle. In order
to improve the efficiency of manufacture, there is generally
employed a method of at first preparing an ingot of a sufficiently
large cross section, then slicing it into a plate with
predetermined thickness and inclination angle, and finally cutting
it into a predetermined planar dimension.
[0010] Since the FOP has an acute inclination angle of about
30.degree. as mentioned above and also since the glass is brittle
as known well, the FOP with a parallelogram cross section as shown
in FIG. 5 is very easily chipped and is inconvenient for handling
in the manufacture or for use in the fingerprint detection.
[0011] In case the FOP 3 is formed into a circumscribed rectangular
cross section of the parallelogram as shown in FIG. 6A, there is
generated a light non-transmitting area 3a not contributing to the
transmission of the fingerprint image and optically constituting a
shadow. A length L of such light non-transmitting area 3a is given
by L T.multidot.tan(90.degre- e.-.alpha.) for an inclination angle
.alpha. and a thickness T of the FOP 3, and usually becomes larger
than T. In case the thickness T is selected at about 1 mm in order
to withstand the pressure by the finger 10, the length L of the
light non-transmitting area 3a becomes even larger.
[0012] Though it is also possible to construct such light
non-transmitting area 3a as an overhanging portion protruding from
the silicon chip 1 as shown in FIG. 6B, such structure is
unsatisfactory in the strength and in the manufacturing process,
since the FOP is subjected to a bending stress by the pressure of
the finger 10.
SUMMARY OF THE INVENTION
[0013] The present invention has been made in consideration of the
foregoing situation, and an object of the present invention is to
provide a fingerprint input device which can prevent an increase in
the area of the entire device and can simplify the manufacturing
process, thereby enabling a compact configuration of the entire
device.
[0014] The aforementioned object can be attained, according to the
present invention, by forming circuits (peripheral circuits) other
than an image pickup unit, for example a circuit for processing an
output signal of an image pickup unit and a drive circuit for the
image pickup unit, under a light non-transmitting surface namely in
a shadow portion of an inclined fiber optics plate on a
semiconductor substrate (silicon chip) to realize a fingerprint
input device which can prevent an increase in the area of the
entire device and can simplify the manufacturing process, thereby
enabling a compact configuration of the entire device.
[0015] More specifically, the present invention provides a
fingerprint input device including a light source for emitting a
light into the interior of a finger of a fingerprint inputting
person, an image pickup unit for receiving the light emitted from
the light source and scattered in the interior of the finger, and a
peripheral circuit unit connected to the image pickup unit thereby
reading a fingerprint image of the finger based on a light
reception signal of the image pickup unit through the peripheral
circuit unit, the device being characterized in including a
semiconductor substrate bearing an image pickup element
constituting the aforementioned image pickup unit and an
aforementioned peripheral circuit unit, and an inclined fiber
optics plate fixed on the semiconductor substrate, having a surface
on which the finger of the aforementioned fingerprint inputting
person is placed and constituting light transmission means for
transmitting the light, scattered from the interior of the finger
placed on the aforementioned surface, to the image pickup element
along a direction inclined by a predetermined angle, wherein at
least a part of the peripheral circuit unit is formed on the
semiconductor substrate opposed to a light non-transmitting area of
the inclined fiber optics plate.
[0016] In the present invention, the light emitted from the light
source can be any light adapted for use in a fingerprint input
device of in-finger scattering type, and includes, for example, an
infrared light, a near infrared light and a red light. Also the
image pickup element can be, for example, a one-dimensional or
two-dimensional image pickup element. An inclination angle of the
light transmitted in the inclined fiber optics plate, though an
optimum value being variable depending on a refractive index of the
optical fibers constituting the fiber optics plate, is generally
within a range of 20 to 40.degree., preferably about 30.degree., in
case of ordinarily used optical fibers. Also the peripheral circuit
unit includes all or a part of peripheral circuits such as a
circuit for processing the output signal of the image pickup unit,
a control circuit, a light source driving circuit etc.
[0017] At least a part of the peripheral circuit unit is preferably
formed on the semiconductor substrate opposed to the light
non-transmitting area of the inclined fiber optics plate and/or on
the semiconductor substrate which is not contacted with the
inclined fiber optics plate.
[0018] The image pickup unit is formed by an image pickup element
of a predetermined dimension, and is rendered capable of
collectively reading a fingerprint image of the finger placed on
the surface of the inclined fiber optics plate by means of the
image pickup element. In general, the image pickup element
preferably has a dimension within a range of 10 to 20 millimeters
square.
[0019] Otherwise, the image pickup unit is formed by an image
pickup element of a predetermined dimension, and is rendered
capable of reading a fingerprint image of the finger placed on the
surface of the inclined fiber optics plate by means of the image
pickup element, while the finger is made to slide in a
predetermined direction along the surface. In general, the image
pickup element preferably has a width within a range of 10 to 20
millimeters and a length of several millimeters or less. The
predetermined direction can be, for example, a longitudinal
direction of the finger.
[0020] Fibers constituting the inclined fiber optics plate are
preferably positioned in an inclined manner along a predetermined
direction. The predetermined direction can be, for example a
direction of width of the inclined fiber optics plate.
[0021] The inclined fiber optics plate is preferably covered, in
all the end portions or a part thereof, with an opaque resin.
[0022] A personal authentication system of the present invention is
characterized in utilizing either one of the aforementioned
fingerprint input devices.
[0023] This personal authentication system may also be provided
with fingerprint registering means which registers in advance the
fingerprint image of the finger, read by the fingerprint input
device, as identification information for the aforementioned
person, and fingerprint verification means which verifies whether
the fingerprint image of the finger, read by the fingerprint input
device matches with the image registered in the fingerprint
registering means, and outputs the result of verification as a
personal authentication signal.
[0024] Also an electronic equipment of the present invention is
characterized in employing either one of the aforementioned
personal authentication systems.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIGS. 1A and 1B are perspective views showing configuration
of a fingerprint input device in a first embodiment of the present
invention;
[0026] FIG. 2 is a block diagram showing a circuit configuration
including a peripheral circuit unit;
[0027] FIG. 3 is a perspective view showing configuration of a
fingerprint input device in a second embodiment of the present
invention;
[0028] FIG. 4 is a view showing an entire configuration of a
personal authentication system utilizing a fingerprint input
device;
[0029] FIG. 5 is a cross-sectional view of a prior fingerprint
input device; and
[0030] FIGS. 6A and 6B are cross-sectional views of a prior fiber
optics plate.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0031] In the following, embodiments of the present invention will
be explained with reference to accompanying drawings.
[0032] (First Embodiment)
[0033] FIGS. 1A and 1B are perspective views of a fingerprint input
device in a first embodiment of the present invention. The present
embodiment constitutes an application to a fingerprint input device
of in-finger scattering type.
[0034] Referring to FIGS. 1A and 1B, there are shown a silicon chip
(semiconductor substrate) 1, an image pickup unit 1a formed by a
two-dimensional array of solid image pickup elements such as of CCD
(charge coupled device) or CMOS (complementary metal oxide
semiconductor) provided on the silicon chip, an LED (light emitting
diode) 2 constituting a light source for emitting predetermined
light such as infrared light, near infrared light or red light, an
FOP (fiber optics plate) 3 formed as an inclined fiber optics plate
fixed onto the silicon chip 1, a substrate 4 on which the silicon
chip 1 is fixed, wires 5 electrically connected to plural
electrodes on the silicon chip 1, a sealing resin 6, a finger 10 of
a fingerprint inputting person, and a fingerprint 10a of the finger
10.
[0035] The solid image pickup elements constituting the image
pickup unit 1a have a pitch of array of generally 50 micrometers
(.mu.m) or less, since a fingerprint input device requires, as an
input condition for a fingerprint image, a resolution of 500 dpi
(dot per inch) or higher.
[0036] The LED 2 is provided in a position capable of emitting
light toward the interior of the finger 10 of the fingerprint
inputting person, placed on the surface of the FOP 3.
[0037] There are also shown a peripheral circuit unit 1b including
all or a part of circuits for controlling the image pickup unit 1a,
processing the output signal and a control circuit for the LED 2
serving as the light source, and plural electrodes 1c for
connecting circuits such as the image pickup unit 1a and the
peripheral circuit unit 1b with circuit elements such as a circuit
provided outside the silicon chip 1 and a power supply.
[0038] An example of the configuration of the circuits, including
the peripheral circuit unit 1b formed on the silicon chip 1 is
shown in a block diagram in FIG. 2.
[0039] Referring to FIG. 2, there is shown the aforementioned
peripheral circuit unit 1b formed on the silicon chip 1. The
peripheral circuit unit 1b includes a control circuit (drive
circuit) 11 for controlling the function of the image pickup unit
1a, an A/D converter 13 for converting an analog image signal,
corresponding to an image of the fingerprint 10a of the finger 10
outputted from the image pickup unit 1a, into a digital signal
through a clamping circuit 12, a communication control circuit 14
for communicating the digital signal, converted in the A/D
converter 13, as an image signal of the fingerprint 10a to a
external apparatus (such as an interface), a register 15 connected
to the communication control apparatus 14, an LED control circuit
16 for controlling the light emission of the LED 2, and a timing
generator 17 for generating control pulses for controlling
operating timings of the aforementioned circuits 11-16, based on
reference pulses supplied from an external oscillator 21. The
circuits including the peripheral circuit unit 1b are not limited
to those described above but may include circuits of other types.
Also a part of the aforementioned circuits may be provided on an
unillustrated separate chip.
[0040] Now the functions of the aforementioned fingerprint input
device will be explained with reference to FIGS. 1A, 1B and 2.
[0041] At first, the finger 10 of the fingerprint inputting person
is placed on the FOP 3, and the LED 2 emits light such as infrared
light, near infrared light or red light according to a control
signal from the LED control circuit 16, toward the interior of the
finger 10.
[0042] The light is scattered in the interior of the finger 10,
then is introduced and transmitted along the inclination angle
.alpha. of the FOP 3, as an optical signal corresponding to the
fingerprint image of the fingerprint 10a, and is transmitted to the
image pickup unit 1a through a light transmitting surface 3b.
[0043] The signal received by the image pickup unit 1a is read as
an analog image signal according to a drive signal from the control
circuit 11, then is converted through the clamping circuit 12 into
a digital signal by the A/D converter 13, and is outputted, as
fingerprint image data reflecting the fingerprint 10a of the finger
10 of the fingerprint inputting person, to the exterior by the
communication control circuit 14.
[0044] In the following, there will be explained an example of
arrangement and design of the circuits of the fingerprint input
device.
[0045] As shown in FIG. 1A, an FOP 3 of an inclination angle
.alpha. (for example about 30.degree.) and a thickness T (for
example about 0.5 to 1 mm) is fixed by adhesion onto the silicon
chip 1. In this arrangement, among the light non-transmitting
surfaces of the FOP 3, at least a light non-transmitting surface
(light non-transmitting area) 3a at a side opposed to the silicon
chip is so positioned as to cover all or a part of the peripheral
circuit 1b.
[0046] The silicon chip 1 is fixed by adhesion to the substrate 4,
then the electrodes 1c and electrodes (not shown) on the substrate
4 are connected by the metal wires 5 utilizing the known wire
bonding technology, and the sealing resin for protection is coated
and hardened.
[0047] The image pickup unit 1a has an area of about 10 to 20
millimeters square, and an area of the FOP 3 is larger by the light
non-transmitting area 3a.
[0048] The thickness T of the FOP 3 preferably is preferably
maintained at a minimum value not breakable by the pressure with
the finger 10 in consideration of the imaging performance and the
production cost, and is generally selected within a range of about
0.5 to 1 mm.
[0049] The length L of a side of the light non-transmitting area 3a
is about 0.9 to 1.7 mm in case the inclination angle .alpha. of the
FOP 3 is selected about 30.degree..
[0050] Therefore, in the present embodiment, by suitably selecting
the circuit magnitude and the design rule of the peripheral circuit
unit 1b in such a manner that the length of a side thereof is equal
to or larger than the length L of the light non-transmitting area
3a of the FOP 3, there can be realized a fingerprint input device
without generating an ineffective area on the silicon chip 1 by the
light non-transmitting area 3a, and also satisfactory in the
strength of the FOP 3.
[0051] In this manner, by forming the peripheral circuit unit 1b
other than the image pickup unit 1a, such as the circuit for
processing the output signal of the image pickup unit and the drive
circuit for the image pickup unit, under the light non-transmitting
surface namely in the shadow portion of the FOP 3 to realize a
fingerprint input device which can prevent an increase in the area
of the entire device and can simplify the manufacturing process,
thereby enabling a compact configuration of the entire device.
[0052] In the aforementioned fingerprint input device, in case an
unnecessary light (not shown) enters the light non-transmitting
area 3a from an end portion of the FOP 3, it may reach the
peripheral circuit unit 1b. It is generally known that a
semiconductor device, under a strong light irradiation, may
generate a leak current thereby resulting in an erroneous operation
of the circuit. For preventing such phenomenon, it is usual to
provide a light-shielding layer such as an aluminum film on the
peripheral circuit unit 1b.
[0053] In the present embodiment, the sealing resin 6 is made
opaque to the light and is made to cover all or a part of the end
portion of the FOP 3. In this manner it becomes unnecessary to form
a light shielding layer thereby simplifying the manufacturing
process of the semiconductor chip and reducing the cost
thereof.
[0054] (Second Embodiment)
[0055] FIG. 3 is a perspective view of a fingerprint input device
of a second embodiment of the present invention.
[0056] In the fingerprint input device shown in FIG. 3, as in the
first embodiment, a peripheral circuit unit is provided on the
silicon chip 1, on which the FOP 3 is fixed, in a position
corresponding to the light non-transmitting portion of the FOP 3,
but, in contrast to the first embodiment in which the fingerprint
10a of the finger 10 of the fingerprint inputting person placed on
the FOP 3 is collectively read, there is employed a sweeping method
in which the finger 10 is made to slide along a longitudinal
direction thereof, for example in a direction indicated by an arrow
10b in FIG. 3, thereby entering the fingerprint image in succession
(substrate 4, wires 5 and sealing resin 6 being similar to those in
the first embodiment).
[0057] Referring to FIG. 3, an unillustrated image pickup unit 1b
is constituted of solid image pickup elements of a resolution same
as that of the first embodiment, arranged in an array of a width of
10 to 20 mm and a length of several millimeters in the
perpendicular direction. In the present embodiment, the FOP 3 has
an inclination angle .alpha. only in a direction of width.
[0058] Thus the present embodiment, being applied to the
fingerprint input device of sweep method and decreasing the areas
of the silicon chip 1 and the FOP 3 as explained above, can realize
an extremely compact and inexpensive fingerprint input device. Also
the inclination angle .alpha. is provided only in the direction of
width to prevent an increase in the longitudinal dimension of the
silicon chip or the FOP.
[0059] Also in the present embodiment, it is possible to dispense
with the light shielding layer on the peripheral circuit unit, as
in the first embodiment, by employing an opaque resin for the
sealing resin 6 provided for protecting the electrodes at the end
of the silicon chip 1 and the wires 5 connected thereto, coating
such resin so as to cover the end portion of the FOP 3.
[0060] In the following, there will be explained, with reference to
FIG. 4, an example of application of the aforementioned fingerprint
input device to a personal authentication system.
[0061] A personal authentication system shown in FIG. 4 is provided
with a fingerprint input device 100 including an image pickup unit
1a, a peripheral circuit unit 1b and an LED 2 as explained in the
foregoing, and a fingerprint verification device 110 connected to
the fingerprint input device 100. The fingerprint verification
device 110 is provided with an input interface 111 for entering
communication data outputted from the communication control unit of
the peripheral circuit unit 1b, an image processing unit
(fingerprint verification means) 112 connected to the input
interface 111, a fingerprint image database. (fingerprint
registration means) 113 connected to the image processing unit 112,
and an output interface 114. The output interface 114 is connected
to an electronic equipment (also including a software) which
requires a security at use or at login.
[0062] The fingerprint image database 113 registers in advance the
fingerprint image of the finger of an object person who is to be
individually identified. The object person may be a single person
or plural persons. The fingerprint image of the object person is
entered in advance, as the personal authentication information of
the object person, from the fingerprint input device 100 through
the input interface 111, at the initialization or at the addition
of an object person. The image processing unit 112 receives the
fingerprint image, read by the fingerprint input device 100,
through the input interface 111, then executes verification as to
whether the fingerprint image matches with the image registered in
the fingerprint image database 113 based on a known fingerprint
verifying image processing algorithm, and outputs the result of
verification (whether the fingerprints match or do not match) as a
personal authentication signal through the output interface
114.
[0063] In the present example, the fingerprint input device 100 and
the fingerprint verification device 110 are constructed as separate
devices, but the present invention is not limited to such
configuration and at least a part of the functions of the
fingerprint verification device 110 may be integrally constructed
in the peripheral circuit unit 1b of the fingerprint input device
100. Also the personal authentication system of the present example
may be integrally constructed in the electronic equipment requiring
the personal authentication or may be constructed separately from
the electronic equipment.
[0064] According to the present invention, as explained in the
foregoing, at least a part of the peripheral circuit unit is
provided under a light non-transmitting surface of an inclined
fiber optics plate on a semiconductor substrate to realize a
fingerprint input device which can prevent an increase in the area
of the entire device and can simplify the manufacturing process,
thereby enabling a compact configuration of the entire device.
* * * * *